title: Unknown primary tumors.
abstract: An unknown primary tumor (UPT) is defined by the presence of a metastatic cancer without a known primary site of origin despite a standardized diagnostic workup. Clinically, UPTs show rapid progression and early dissemination, with signs and symptoms related to the metastatic site. The molecular bases of their biology remain largely unknown, with no evidence as to whether they represent a distinct biological entity. Immunohistochemistry remain the best diagnostic tool in term of cost-effectiveness, but the time-consuming "algorithmic process" it relies on has led to the application of new molecular techniques for the identification of the primary site of UPTs. For example, several microarray or miRNA classifications of UPTs have been used, with an accuracy in the prediction of the primary site as high as 90%. It should be noted that validating a prediction of tissue origin is challenging in these patients, since most of them will never have a primary site identified. Moreover, prospective studies to determine whether selection of treatment options based on such profiling methods actually improves patient outcome are still missing. In the last few years functional imaging (i.e. FDG-PET/CT) has gained a main role in the detection of the site of origin of UPTs and is currently recommended by the European Association of Nuclear Medicine. However, despite recent refinements in the diagnostic workup, the site of origin of UPT often remains elusive. As a consequence, treatment of patients with UPT is still empirical and inadequate.
authors.affiliation: Unit of Medical Oncology, Department of Oncology and Experimental Medicine and CeSI, Fondazione 'G. D' Annunzio', University of Chieti-Pescara, 66100 Chieti, Italy. natoli@unich.it
authors.forename: C
authors.initials: C
authors.lastname: Natoli
authors.forename: V
authors.initials: V
authors.lastname: Ramazzotti
authors.forename: O
authors.initials: O
authors.lastname: Nappi
authors.forename: P
authors.initials: P
authors.lastname: Giacomini
authors.forename: S
authors.initials: S
authors.lastname: Palmeri
authors.forename: M
authors.initials: M
authors.lastname: Salvatore
authors.forename: M
authors.initials: M
authors.lastname: Landriscina
authors.forename: M
authors.initials: M
authors.lastname: Zilli
authors.forename: P G
authors.initials: PG
authors.lastname: Natali
authors.forename: N
authors.initials: N
authors.lastname: Tinari
authors.forename: S
authors.initials: S
authors.lastname: Iacobelli
mesh_terms: D000818:Animals; D020869:Gene Expression Profiling; D006801:Humans; D035683:MicroRNAs / Q000032:analysis; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology / Q000628:therapy
chemical_list: D035683:MicroRNAs